380 PATHOLOGY Seats of times be seen (as in the mamma of the bitch) the most remarkable development of all, the change of the cartilage into bone, with perfect medullary spaces lined by perfect osteoblasts. There are, indeed, no limits, other than the fundamental embryological limits, to the formative possibilities of cells which have reverted to primitive embryological function. We have already seen that the standing example of an embryonic tissue, the spindle-celled tissue of the ovary, contains within itself the whole range of development which is expressed in the grotesque variety of a dermoid cyst. Another common effect of disordered glandular function is the excessive formation of solid by-products of the secretion, which are either retained in the recesses of the gland or are infiltrated into the spaces of the underlying and supporting connective tissue. Where the products arc retained within the gland-space we have the familiar and simple result of cysts from retention, of which the sebaceous cysts or " wens " of the scalp are good examples. But a far more momentous occurrence is the infiltration of these crude pro ducts or by-products of secretion into the depth. We have already found reason to believe that the same kind of infiltration below the surfact takes place in catarrhs, that the nuclear cells found in the deeper layers of a thickened mucous membrane arc of the same origin as the catarrhal cells of the surface-discharge, and that their presence in the spaces of the connective tissue had been the excit ing cause of the fibres becoming thick and coarse, or, in other words, of the "inflammatory" changes in that tissue. The infil tration which conies under our notice in tumours of secreting structures is different from this as regards the characters and pro perties of the cells : as regards their characters, the cells retain more of the epithelial type, that is to say, they are not naked nuclei, but they have a considerable investment of cell-substance ; as regards their properties, these epithelial cells infiltrated below the nmcosa do not excite " inflammation," but they excite cancer. What remains to be said of the infiltration of by-products of glandular secretion will be included in the section on cancer immediately following. 8. CAXCEE. The popular estimate of the nature of cancer is so well founded that a definition is superfluous. Cancer in patho logical anatomy differs from cancer as commonly under stood in being restricted to the malignant tumour-diseases of secreting structures and epitheliated surfaces generally, to the exclusion of a certain number of equally malignant tumours which grow from the periosteum or the marrow of bone, or from other mesoblastic tissues. The great majority of all the cases which have the fatal progressiveness of cancer are diseases of the stomach, the uterus, the breast, the intestine, and the skin ; this group makes so large an element in the sum-total of tumour-disease, and is so homo geneous within itself, that it may justly appropriate the name of cancer, leaving the other cases of tumour-malig nancy to be described by- more technical names. At the same time it should be clearly understood that the smaller detached group does contain cases where the particular man ner of fatal progression is not different from the progressive- ness of the epithelial tumour-disorder, such, for example, as the cases of periosteal tumours becoming parosteal. Chief Scats of Cancer. The absolute and relative frequency of cancer in the various seats of secretion has been ascertained by D Espine, from the mortality returns of the canton of Geneva, for both hospital patients and the well-to-do treated at home, to be as follows over the period from 1838 to 1855 : Stomach 300 cases, or 45 per cent. Uterus 130 ,, 15 Liver 03 10 5 Breast 70 , , s-5 Bmall and large intestine : J ,0 3-3 Rectum 25 ,, 3 being 762 or 85 3 per cent in a total of 889 cases of malignant tumours of all sorts. Most cases of cancer of the liver are really secondary to cancers in the stomach or elsewhere, so that the leading position of the stomach, and after it of the uterus, the breast, and the intestine, becomes more marked. According to the facts collected by Yirchow from the mortality returns of the town of Wurzburg from 1852 to 1855, the deaths from malignant tumours were 5 3 per cent, of the total mortality, and the percentages among malignant tumours were as follows : Stomach 34 -9 per cent. Uterus, &c 18 5 Intestine S l Liver, <tc 7-5 Face and H;K 4-9 M Breast 4-:j 78-2 per cent, of all malignant tumours. It may be accepted, then, that the digestive tract is the seat in about one-half of the cases of malignant tumour -disease, and the female sexual organs (excluding the ovaries, but including the breasts) in about one -fourth, while the remaining fourth has to be apportioned among other epithelial organs or parts and the bones and other mesoblastic tissues. It must not be supposed that these ratios hold good equally for all localities ; the breast sometimes appears to usurp a larger share, and sometimes the rectum. Again it is a noteworthy fact that cancer is a comparatively rare disease among the vast populations within the tropics. The beginnings of cancer have to be sought for in disturbances of the apparatus and process of secretion. Even in the cases where hereditary or congenital predisposition plays a part there must have been local irregularities of structure and function to deter mine the seat of the disease ; thus, of four sisters of whom three were married and had families, one died of cancer of the breast, another of cancer of the stomach, a third of cancer of the rectum, and the fourth of cancer of the uterus, the incidence of the disease in them all happening about the age of fifty to sixty. Cancer in secreting structures is essentially one process ; but each of the favourite seats of cancer has its own special liability, as Avell as points of structure special to itself. The liability of the female breast is an entirely different tiling from the liability of the stomach ; and the liability of the uterus is more closely allied to that of the stomach than to that of the breast, although the breast and the uterus have a closer systemic relationship. There is, however, something in the cellular law of secretion common to them all, and it is that common feature of the secretory process which first engages the attention. Relation of Cancer to Secretory Process. The product of secretion Cancel is not, under all circumstances, a fluid; in the simpler forms ofandtb animal life, and in more recent or less elaborated glands of the secrete higher forms, it may be thrown off in cellular shape, just as it is proces always cellular in its origin. We have already seen that in the catarrhal state the cellular admixture is considerable, and there can be hardly any question that the cells of a catarrhal discharge are derivatives of the epithelial cells, being indeed little other than their nuclei. We have also seen reason to believe that the infiltration of nuclear cells in the thickened mucous membrane of chronic catarrh had been a real infiltration of the catarrhal cells beneath the surface. Xow the favourite seats of chronic catarrh, the stomach and the uterus, are also the favourite scats of cancer. What, then, is the relation between these two very different diseases, both of them primarily disorders of the apparatus and process of secretion ? A particular case will bring out the points of resemblance and the Diffuse points of difference. In a fatal case of cancer of the stomach the cancer whole organ is found to be uniformly thickened, the mucous mem- whole brane being much ridged and furrowed ; but its epithelium is un- stomat broken. The interval of submucous tissue, ordinarily a loose layer between the mucosa and the muscular coats, is occupied through out the whole extent of the organ by a nearly uniform stratum of firm whitish tissue. This is an exceptional case of cancer of the stomach, but it is a very instructive one ; the morbid condition is as uniformly diffused over the organ as if it had been the thickening of chronic ca tarrh, and it wants the usual tumour - char acter of cancer. The micro scopic exami nation proves, whatthewhite- ness and almost gristly firmness of the submu cous interval had suggested, that the disease is hard cancer. The white stra tum iimlpr flip un, 4 , mucosa has the structure shown in the cut (fig. 48), and it is an average example of the infiltration of scirrhous cancer. Epithelial -like cells, with a disproportionately large nucleus, are as if packed in rows in the spaces of a very dense fibrous tissue, which contains a large number of elastic fibres. Besides the linear processions of cells, there are elsewhere groups of them arranged round the walls of spaces like the epithelium of a gland. Throughout the whole thickness of the coats of the stomach in this case such collections of cells are found ; in the muscular coats they are met with chiefly where there are fibrous septa ; and it is noteworthy that the gland- like collections are by far the most numerous in the tissue most 48. Indltration of scirrhoug cancer uniformly diffused throughout the whole sub-nmcosa of the stomach.
